Storage pile and method of producing same



Aug. 5, 1941. w. T. BROWN' 'STORAGE PILE `AND METHOD OF PRODUCING SAME Filed May 18. 1939 grt/vento@ m Z IK Patented Aug. 5, 1941 zits-1312i."

' STORAGE PILE ANDMETHOD 0F f i f PRODUCING SAME l Walter T. Brown,

Hackensack, N. J., assignor to Bethlehem Steel Company, a corporation of Pennsylvania Application May 1s, 1939, seria1N0.274,346

8 Claims.

My invention relates to the storage of coal.

More specically my invention relates to a method of storing coa1 to prevent oxidation and spontaneous combustion thereof. l

It is well known that all coals undergo spontaneous heating in storage, due to oxidation.

Such oxidationV proceeds slowly with anthracite coals, but; is very marked with bituminous coals and is particularly harmful to bituminous coals which are intended to be coked. Only a small amount of oxidation is necessary to destroy the coking properties of low and medium volatile coals, and decrease the yield of their most valuable by-products such as'phenols and `cresols.

While the extent to which coa1 will oxidize in storage depends in part upon the nature of the coa1 itself, it also ldepends in part on other factors. I have found that the rate of oxidation increases as the size of the coa1 particles decreases. I have also found that wet or damp coa1 oxidizes faster than dry coa1.

When coal is stored in a pile, oxidation usually iirst occurs from six to fifteen feet within the pile and travels from there towards the center of the pile. the Apassage of .air currents up through the-pile, which currents oxidize the surfaces of the coal particles. Such oxidation causes a rise in the temperature of the coal, which in turn creates a stack effect in the coal pile and causes air to be drawn through the pile in greater quantities so that oxidation proceeds more rapidly.I Thus oxidation, once started, is a self-sustaining process.

'If oxidation of the coa1 continues for a suf- 35 ciently long time spontaneous combustion of the coal may result. Even if spontaneous combustion does not take place, oxidation has a deleterious eiect on the coa1, as above stated.

Broadly speaking, my invention comprises ar- 40 ranging the coa1 to be stored in a plurality of horizontal superimposed layers, each layer being separated from the one beneath it by a substantially air-tight and waterproof cover.

My invention is more fully described' in the following specification and shown in the accompanying drawing in which' Figure 1 is a plan view of a ing my invention, and

Figure 2 vis a view in vertical section along the line 2-2 of-Figure 1.

Referring to the figures, I0 represents a coal i pile which is separated into a `plurality of layers II, I2, I3, I4 and I5 by the covers I6, I'l, I8, I9 and 20, respectively, each of which envelops coal pile embody- Such oxidation is due primarily to z the'area of the layer immediately beneath it.

Asshown in the vfigures the cover envelopingV each layer of coa1 extends over the sides of such layer -`and may overlap the next lower cover as indicated at 2|. This is not absolutely essential,- however, since substantial benefits are obtained if the covers merelycover the top surfaces of the layers to which they are\app1ied.

Each cover may be formed of any substantially air-tight material, and preferably comprises a plurality of strips 22 which may be of sisalkraft paper or other strong material substantially impervious to air and water. As shown at 23, each strip of paper overlaps the adjoining strip and may, if desired, be cemented thereto. In practising my invention a substantially flat layer of coal is spread on the ground over an 'area suiliciently large to accommodate the quantity of coa1 to be stored. The thickness of the layer is not critical, but is preferably less than ten feet. This layer is then preferably compacted with a roller or bulldozer. This has the eiect of decreasing the air spaces. between the coal particles and also attens the top surface o of the layer so as to render the diaphragm less liable `trainjurymfrom the sharp corners of the coa1. Over this layer of coal a cover of the type hereinabove described is laid. On top of this cover another layer ofcoal is placed, compacted and covered, as above described, and so on until the pile is completed. Although the flattening and compacting of each layer of coa1 is desirable, it is not essential, however, the benets of my invention.

When the coa1 thus stored is needed for use it is preferably removed layer by layer. If the several covers are made of sisal-kraft paper or the likethey may easily betorn away, and are comparatively inexpensive.

It is desirable to cover the top layer of coal I5, as shown in the drawing. This is not essential, however, since comparatively little stack effect and oxidation will take place in.a layer of coal of the order of ten feet thick or less. If

the top layer is left uncovered, the cover immediately beneath it should preferably be sloped somewhat so that rain water will drain therefrom.

By separating a pile of coal into layers by means of substantially air-tight covers, as above described, the circulation of air through the pile is greatly diminished and oxidation is accordingly prevented. Cornpacting andflattening each layer, in addition, tends to minimize the in order to obtain circulation of air,` but this is not essential for the successful practice of my invention.

While my invention is particularly useful for the storage of coal, it is not to be limited thereto,

since it is equally adapted to the storage of other stored into a plurality of comparatively thin superimposed layers and covering the topand sides of each such layer with a substantially airtight covering.

2. The method of storing coal which comprises superimposing upon each other comparatively thin layers of the coal to be stored and separating each such layer from the immediately adjacent layers by means of a substantially air.- tight covering.

3. The method of storing coal which comprises superimposing upon each other comparatively thin layers of the coal to be stored, compacting and leveling the surface of each such layer, and separating each such layer from the immediately adjacent layers by means of a substantially airtight covering.

4. A coal storage pile comprising a plurality of compacted layers of coal superimposed upon each other, each such layer being covered by a. substantially air-tight covering.

5. A coal storage pile comprising a plurality of layers of coal superimposed upon each other, each such layer being separated from the immediately adjacent layers by a substantially airtight covering.

6. A coal storage pile comprising strata of coal and means intermediate the strata for impeding the passage of air through the pile. l.

7. A coal storagepile comprising comparatively thin, horizontal strata of coal and means intermediate adjacent strata for preventing the passage of air therethrough.

8. A coal storage pile comprising a plurality of comparatively thin, superimposed layers of coal, and a substantially air-tight cover for each of said layers.

WALTER T. BROWN. 

